Sharp R-24ST Microwave - Sticking START button

This has been a fantastic oven, but recently the start button has started sticking - you have to press it hard several times to get it to work. At first I thought it might be dirty, but I tried cleaning the area around it and it has made no difference. I guess it needs a new switch - any ideas on how to replace it, please.

Thank you for the follow-up. I haven't had a chance to find out how the control cover comes off yet, because there are no obvious screws. I think your solution is the most like one, and thank you for it. I'm always nervous about Microwaves - these are one of the things that bother me, however I'm reasonably confident and only work withing my ability - besides I'm not going anywher near the magnetron etc. I''ll give it a look hopefully by the weekend and let you know how I get on. More than happy to give you a Fixya, because you've been more than helpful and I'm sure your solution will work.

Thank you,

Gerald

Hi,

Thank you for the follow-up. I haven't had a chance to find out how the control cover comes off yet, because there are no obvious screws. I think your solution is the most like one, and thank you for it. I'm always nervous about Microwaves - these are one of the things that bother me, however I'm reasonably confident and only work withing my ability - besides I'm not going anywher near the magnetron etc. I''ll give it a look hopefully by the weekend and let you know how I get on. More than happy to give you a Fixya, because you've been more than helpful and I'm sure your solution will work.

2 Answers

I had the same problem some years ago, and in my view it is caused by a design fault. There's a circuit board behind the front panel with tiny tactile switches that get pressed by the front panel buttons. But the **** design is that the switches aren't located behind the buttons, so the "engineering solution" that Sharp has used is to mount each of the buttons on a framework so that a sticky out bit from the button presses the appropriate switch. The problem is that the framework is made of plastic and so will eventually give way. Some 5 years ago I opened up my microwave and repaired the framework. When it went again yesterday, it was too far gone to repair. I could purchase a spare button panel from one of the spares suppliers, but for some GBP 8 or so.

Wanting an instant solution, I went a bit further. I removed the switches and soldered short trailing leads to their contacts. I glued (with epoxy) the switches back onto the circuit board so that they were directly behind the buttons, and then soldered the trailing leads from each switch back to the original switch locations. This meant redrilling the holes for one switch as the original holes were now obscured. I then cut off the three buttons from their framework (it was just the Stop, Start and Power level buttons as we never use the others) and trimmed off any projections to make them flush on the back. I filled the hollow of the button with modelling clay, and then expoxied a thin (2mm) layer of rubber on the back. When re-assembled, the buttons simply float in the hole in the front panel, but don't fall out as the switch is just behind them. They now work better than ever before, as they're pressing directly on the switch, rather than indirectly.

For disassembly (from memory), I removed the six or so screws holding on the main steel cover (at the sides and on the rear). There was one screw inside the casing securing the front panel assembly which, when removed, allowed the front panel assembly to be removed by lifting slightly and then pulling out. Disconnect the cable connectors (taking care to label where the yellow & red power connectors go. On the front panel assembley there are two circuit boards on top of each other. Remove the top one and the connector from it to the bottom one. The bottom circuit board is screwed in with 4 screws. Once the bottom board is removed, the button panel lifts out and you're ready to consider whether you're up to my repair method or whether you want to order a new button panel.

It may have taken me a while to complete this, but it gave me the satisfaction of a repair with no parts required, and the confidence that it will last, and can be tweaked if required. So my R24ST lives again!

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If
your appliance has absolutely no functions at all, remove it from the
mains supply, remove the case and see where the mains lead goes in to
the appliance and follow the cable until you find the main fuse.ONLY
USE THE SAME TYPE AND RATING OF FUSE TO REPLACE IT.The usual
cause of this fuse failure is the door switches are contaminated or
sticking. Check the door switches before putting power back on to the
appliance.Hope this helps.

HI, in most cases, the button will be fine. there is an error code that will illuminate on the control if the touch pad starts to malfunction(sticking buttons). this is more likely an issue that concerns the integrity of the fan motor. have it tested. replace it if found to be defective.

This may not solve your problem, but on my Sharp R315J microwave, the little plastic pin that pushes forward on the inside of the start button, had broken off and it wouldn't start. The Minute Plus button would start the microwave, so I knew the microwave worked, so I tried to find a piece of plastic that I could glue into the start button hole, because the part doesn't exist and you have to buy the whole door for $100 plus shipping. Nothing I could find was small enough, so I started looking for a new microwave.
While ouside doing lawn work I noticed a small bird tail feather and the end looked to be the perfect size. I snipped off the pointed end and then up about 3/8" to make a little rod to replace the plastic one that broke. It fit perfectly!!! I didn't even have to glue the inside end, it stays put even after repeated door opens. This is sturdy material and looks to last a long time. When it wears out, I have a cat, there's always a few feathers around. I hope this saves someone else a hundred bucks, like it did me.